An earplug is a piece of protective clothing that is meant to be inserted in the ear canal to protect the wearer's hearing from loud noises or the intrusion of water.

Some earplugs are made of a malleable material that is typically compressed by the wearer's fingers and then inserted in the ear. Once released, the earplug expands until it completely blocks the canal, deadening the sound vibrations that reach the eardrum. This kind of protection is often worn by industrial workers who work within hearing distance of loud machinery for long periods of time. Musicians who perform music styles noted for their loud nature, especially rock music, often wear earplugs to prevent their own performances from deafening them.

Some earplugs are primarily designed to keep water out of the ear canal, especially during swimming. These are typically made of wax, which is custom-fitted to the ear canal by the wearer. Wax plugs also provide some sound dampening.